In our series of letters from African journalists, Joseph Warungu reports that Sunday's presidential election in Tanzania is the most competitive in the country's history.

There are foreign cameras everywhere in Tanzania, and no, they are not taking selfies, instead they are keeping a watchful eye on the country.

In any election, any other year, hardly anyone outside the country's borders would pay any attention to Tanzanians as they vote, because Tanzania is one of the most peaceful and stable countries in Africa.

Presidents are voted into office and leave without a strong military hand or popular protests shoving them out the door.

Since independence Tanzania has had four presidents who between them have served a total of 54 years.

'Jumped ship'

But this election is different and a number of factors have combined to turn the sleepy Tanzanian political landscape into an intense battlefield.

To begin with, for the first time ever, the main opposition parties, including Chadema, have joined forces to support one candidate for the presidency.

Image copyrightCCMImage caption
CCM campaigners do press-ups to show their candidate John Magufuli is healthy and fit for office

Image copyrightChademaImage caption
Candidates are using helicopters to get to rallies across the vast country - this is Chadema's official Twitter photo

This opposition umbrella is known by its Swahili acronym, Ukawa.

In 2002 in neighbouring Kenya, a similar opposition umbrella group delivered a fatal blow to the ruling Kanu party, which had been in power for 40 years since independence.

Secondly incumbent Jakaya Kikwete has to leave office having served the maximum two five-year terms allowed by the constitution, so the stage is set therefore for a new president.

Thirdly, Edward Lowassa, a key figure in the ruling CCM party, and who served as prime minister, jumped ship shortly before the campaigns and is the now the greatest challenge to the party.

He is Ukawa's presidential candidate and he knows the spots that hurt within CCM.

Fourthly there is the youth factor and the undecided voters: More than half of the 22,750,789 registered voters are aged between 18-35 years.

Many of them are first-time voters - which means no-one can tell which way their vote will go.

Unlike other elections, modern campaign methods are all the rage in this election.

The use of helicopters by the main parties and some prominent candidates makes it easy to criss-cross this vast country and hold a number of rallies each day.

Social media is a key frontier to conquer in this election and a strong web presence is mandatory.

Finally, there is the money factor.

Judging by the amount of live radio and TV advertising that has been purchased by the parties and candidates, as well as the forest of party posters, banners, billboards and flags everywhere, it is clear the main parties are loaded with cash.